ATI's Charisma Engine

ATI's Charisma Engine - Page 2


Introducing ATI's Next Generation Technology

The ATI Charisma Engine and Pixel Tapestry Architecture


Skinning the bones - Matrix Skinning

Vertex Skinning is a method of of literally stretching a "skin" if you will, over the gaps in the joints of a character on your screen.  Groups of polygons joined together to produce a character, will still have visible gaps in them when the character moves and bends its joints.  Skinning smoothes out the coarse and sharp joint areas of the character as it moves. 

This is a representation of an image Skinned with 2 Matrix Skinning (the current NVidia way) and 3 Matrix Skinning as will be available with the R6 Charisma Engine.

As you can see, the effect of 3 Matrix Skinning is indeed much better.  The Charisma Engine will have 4 Matrix Skinning available in hardware, which will be a step up from even this representation.



Flipping Frames - Keyframe Interpolation

Keyframe Interpolation helps move a character from one position to another and shows the subtle differences of the changing character's image for each frame that is rendered from the original frame to the destination image.  Here is an example...

The Charisma Engine will allow Developers to insert as many "interpolated frames" as the want in between the original and destination "key frames".  This will produce smooth and gradual transitions in areas like facial expressions, as you see above.



Making Pretty Pixels - Pixel Tapestry Architecture

ATI's Pixel Tapestry Architecture will provide for three texture units per rendering pipeline.  As a result, the engine can blend and filter up to three textures per pixel at full speed without a performance hit.  They are calling this the world's first "Gigatexel Engine".  With this architecture they can support a host of new features including...

  • Emboss Bump Mapping

  • Dot Product Bump Mapping

  • Environment Bump Mapping

  • Priority Buffer Support - Assist with Shadow Mapping

  • 3D Textures

These are examples of various types of Bump Mapping.  ATI's Pixel Tapestry will accelerate all of these methods.

Each method has its own place and functionality.  Environmental for reflections, Dot Product for texture and emboss for contouring effects.

The Priority Buffer is used to cast shadows for multiple objects in a scene, in order of closeness to their light source.  In addition you can also achieve other effects like "Self Shadows" where a character's arm, for example, will cast a shadow against its body.

This will be big - 3D Textures

Finally, 3D Textures are a great new addition and are just what you may think they are from their name.  3D Textures add another dimension to 2D textures which are used to "wrap" around an object or character, adding substance to flat polygons.  3D Textures have the dimension of "volume" as well.  An example of this would be if you chipped off a piece of marble wall and exposed the material under the surface as well as the surface texture. Think also about a character getting wounded.  The imagery could almost be sickening...  The third "volume dimension" would be require an update of the 2D Texture to cover the new surface area exposed.  The 3D texture does not require this update, as it has another surface area below the top surface.  You can chip or cut away from an object freely with out additional operations.

Final Important Details and A Wrap-Up

There are a few things that also should be noted and struck us as very interesting with respect to this new technology announced by ATI.  First, here is a Feature Support chart of the ATI Charisma Engine versus the NVidia GeForce.

Source: ATI Technologies

Update 3/9/00

The NVIDIA GeForce does indeed support Range Based Fog and Shadow Mapping

This clearly looks like, at least on paper, ATI is about to break out of the pack.  Also here are a few additional notables.

  • The new R6 - Charisma Engine and Pixel Tapestry Architecture will be available in Q2 '00  ( That is only 3 months away, max )

  • ATI will provide all of this new technology in a single chip solution.  There will be no need for a multiple ASIC approach.


Well, that is about all we have for now folks.  We'll stay tuned to the GDC event and keep you posted with any further developments on this exciting new product and platform from ATI.

You can download ATI's White Paper on this new technology.  Get the White Paper here.  (Word Document - 4.6MB zipped and ribbed for your pleasure.)

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Tags:  ATI, engine, AR

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